# yii\debug\widgets\history

> 2 classes of the yii\debug\widgets\history namespace.

[API reference](/docs/api/index.md) › [Debug](/docs/extensions/debug/reference/index.md) › [widgets](/docs/extensions/debug/reference/widgets/index.md) › history

## Classes

| Class | Summary |
| --- | --- |
| [`HistoryComparison`](/docs/extensions/debug/reference/widgets/history/historycomparison/index.md) final readonly | Builds a privacy-preserving comparison of two immutable debugger snapshots. |
| [`HistoryRowRenderer`](/docs/extensions/debug/reference/widgets/history/historyrowrenderer/index.md) final | Renders the History index summary header + the per-cell HTML consumed by the GridView columns and the typed `rowOptions` builder. |